In a furniture spring assembly of this type, a series of sinuous spring bands are normally stretched between the front and back rails of a seat frame in parallel, spaced relationship. The bands may be attached to the rails by conventional anchor clips stapled or nailed on the top surface of each rail or by other conventional means. In the alternative, they might be attached in the manner illustrated in U.S. Pat. No. 3,790,149, issued Feb. 4, 1974, entitled SPRING CONSTRUCTION, or U.S. Pat. No. 3,773,310, issued Nov. 20, 1973, entitled SPRING CONSTRUCTION, both illustrating furniture spring assemblies including sinuous spring band attachment assemblies and clips developed by the applicant.
Where either the front or back rails, or both, are curved, however, the effective anchoring of sinuous spring bands to the curved rail(s) is more difficult. The linear end segments of a band will not mate properly with clips which are conventionally fastened to the rails, for example. The effective anchor point on each end of a band ends up being out of longitudinal alignment with the center line of the band, producing uneven spring resilience when a person sits on the furniture spring seat. In addition, other related complications in spring attachment and performance are created by curved rails in furniture seats. For example, conventionally it has been necessary to use a plurality of different spring band lengths. It is also frequently necessary to attach a clip in close quarters under a back stuffing rail, which is normally immediately over the back frame rail in curved rail goods.